Currently, a projection display device has been widespread in practical use. In such a display device, not only a bright image, but also a dark image tend to become brighter when the brightness of an image displayed on a screen is enhanced.
Recently, a liquid crystal display device comprising a first liquid crystal panel displaying an image and a second liquid crystal panel uniformly adjusting an amount of light on an entire screen between a light source and the screen has been proposed. In a configuration of uniformly adjusting the amount of light on the entire screen, however, if a bright portion and a dark portion are present together in an image (moving image or still image) displayed on the screen, adjustment of the amount of light in accordance with the brightness at each of the bright portion and the dark portion is difficult.
Thus, there has been a demand for enhancement of the brightness at the bright portion of the image displayed on the screen and a reduction in the brightness at the dark portion to improve the display quality.